Process of applying finishes to metallic sheets and the like



Oct. 6, 1936. RPM. FENTON PROCESS OF APPLYING FINISHES TO METALLICSHEETS AND THE LIKE Filed Aug. 8, 1952 Fatenteol @ct. 6, l fi untruestares attain Parent IPRGCIESS @IF AiPlPlLlYlING FINISHES Till) METALLECSHEETS AND THE MIKE 1 Claims.

This invention relates as indicated to the process of applying finishesto metallic sheets and the like and refers more specifically to aprocess for producing metallic sheet metal having a uniformsubstantially smooth surface such as is required in the manufacture ofautomobile bodies and like articles, where the nature of the coatingultimately applied to such sheets requires that the same be as nearlyperfect as possible in order that no imperfections in the surface of themetallic sheet may be reflected in the paint or like finish ultimatelyapplied thereto.

In my Patent No. 1,995,382 which issued on my copending application Ser.No. 509,563, filed Jan. 19, 1931, is disclosed an apparatus capable ofsubjecting the surface or surfaces of a metallic sheet and/or strip ofsteel or like material to a uniform abrading action throughout theextent of such surface and the process comprising my invention andpresently to be explained more in detail contemplates the employment ofsuch a machine for the purpose of abrading the surface of the sheet asone step in the-process.

The above identified apparatus is particularly 2 desirable for thepurpose of performing one of the steps of the process presently to beexplained for the reason that such machine may be employed to rapidlyand efficiently abrade the sheets so that not only may productionproceed in the 30 usual manner and at the usual rate common in steelmill practice but such apparatus is particularly adapted for largescale, low cost operation.

As is well known to those familiar with the art of sheet steelmanufacture, the surface of the sheets may, either during the rollingoperation or during any of the other steps in the process of itsmanufacture, have imperfections formed thereon such as might be due tothe inclusions of flakes of scale in the surface or the formation oflines on the surface of the sheet due to crowding of the metal as thesame passes through the rolls. Other imperfections are equally wellknown to those familiar with the art and it is one of the objects of myinvention to provide a. process for applying a finish to metallic sheetswhich will not only remove such imperfections but will produce a finishsuperior to any'achieved by means heretofore employed.

As is likewise well known to those familiar with the art, the productionof full finish steel sheets is not possible in a straight linecontinuous manner by apparatus at present employed, for the reason thatthe sheets, in being rolled and heated, have adhering to their surfacesconsiderable quantities of scale which, at the present time, is

removed by bundling such sheets, placing the same on trays and thenimmersing the same in an acid bath in order to remove such scale beforethe final finishing steps in the complete process may be performed. Thisinterruption of 5 the continuous straight line movement of the sheetsprevents the sheet making process from being carried on as a fullcontinuous operation without the installation of enormously expensiveequipment which has limited straight line producl tions in this countryto only a few isolated installations.

By the employment of the process comprising my invention, the process ofproducing full finish sheets may be carried on continuously in a 15straight line production manner without the necessity for heavyinvestments in equipment.

Even though extensive pickling is resorted to in order to remove scaleinclusions in the surface of the sheets, prior to a cold rollingoperation employed for the purpose of imparting a full finish to suchsheets, nevertheless, it has been found that when such scale inclusionsare considerable in area and depth, thereby producing a materialindentation in the surface of the sheet, the pickling step may removesuch scale inclusion but the subsequent cold rolling operation is notsufficient to remove the traces of such defect. This is believed to bedue to the fact that a cold rolling operation is incapable of supplyingthe necessary material required to fill out such indentations so thatinstead of removing all traces of the imperfection, the cold rollingoperation has a tendency to aggravate the blemish in the sheet.

As is likewise well known to those familiar with the art, one of thedifficulties inherent in socalled strip steel which has been reduced bycold rolling under high pressures is that the mirrorlike finish of suchstrip is unsuited to have applied thereto a coating of certain types ofenamel, paint, etc. By the operation comprising my vention it ispossible to convert such mirror-like surface found on sheets and/orstrips into a surface which is sufficiently open to permit the readyadherence thereto of finished coats such as the above-mentioned.

It is among the objects of my invention to provide a process forapplying finishes to metallic sheets which shall be capable of producingsheets having all of the above-named desirable characteristics. Otherobjects of my invention will appear as the description proceeds. I

To the accomplishment of the foregoing and related ends, said invention,then, consists of the ll steps hereinafter fully described andparticularly pointed out in the claims:

The annexed drawing and the following description set forth in detailone approved method of carrying out the invention, such disclosedmethod, however, constituting but one of the various ways in which theprinciple of the invention may be used.

In said annexed drawing:

Fig. 1 is an illustration of a micro-photograph showing the surface ofthe steel sheet magnified 50 diameters and showing such surface afterthe same has been subjected to the abrading action, which is one step inthe process comprising my invention; Fig. 2 is a micro-photograph of thesame surface illustrated in Fig. 1 but magnified only 6 diameters; andFig. 3 is the same surface as has been illustrated in Fig. 2 magnified 6diameters but after such surface has been subjected to a cold rollingoperation.

The process comprising my invention generally stated comprises the stepsof subjecting a metallic v sheet which has surface imperfections to anabrading action such as would be produced by the apparatus disclosed andclaimed in my aforesaid patent. As most clearly illustrated in Fig. 1,this abrading action upon the sheet has a tendency to produce a surfacewhich, when magnified many times, has a plowed effect, i. e., thesurface of the sheet has been disturbed to form a large number of veryfine longitudinally extending ridges. In subjecting the sheet to suchabrading action, however, all or approximately all of the scale normallyadhering to the surface of the sheet is mechanically removed and wherethere have been indentations due to excessive scale inclusions, themetal is plowed over so that such inclusions are substantially filled inand a sheet having a uniform roughened finish is produced.

After the scale has been removed in the above defined manner and thesheet roughened by the abrasive action, the same is subjected to a coldrolling operation with the line of movement of the material through therolls in substantial alignment with the direction of the grooves formedby the abrading action. This cold rolling step flattens out the groovesformed by the abrading action and the resultant sheet, as most clearlyillustrated in Figure 3, possesses a uniformly smooth finish which couldnot be secured were the scale of the sheet removed by pickling and thesheet then subjected to simply a cold rolling operation.

In certain cases, it may be found necessary to cleanse the sheet afterthe abrading step and before the cold rolling operation for twoprincipal reasons, namely, the abrading action on the sheet may notextend deeply enough into the surface to remove all scale inclusions inslight pits and similar imperfections. A subsequent pickling operationwill, therefore, be necessary or at least desirable in order to removethe scale which has not been reached during the abrasive action. Theother reason for the cleansing action following the abrading action isto remove all adhering foreign material which may have a tendency toremain on the surface of .the sheet after it has been abraded.

In any event, however, the type of pickling required to cleanse afterthe abrading operation need not be very severe so that the step commonlyreferred to in the art as a wash picking process may be employed toproduce this cleansing action. By wash pickling is meant conveying thesheets and/or strip through a suitable acid bath but due to the factthat most of the scale has been removed by the abrading action and onlyminute inclusions of scale and loosely adhering foreign material need beremoved from the sheet, such. wash pickling action is sufficient toproperly cleanse the surface and as is well known to those familiar withthe art, wash pickling does not ordinarily result in any appreciableetching of the metal.

After the wash pickling step, it is usually desirable to scrub and drythe surface in the manner well known in the art, so that the sheet maybe perfectly clean before it passes into the cold rolls.

As an example of several specific applications of the process comprisingmy invention, several cases will be considered wherein such process maybe employed in the production of finished sheets.

One set of operations which may admirably include the process abovedefined, consists of the following steps preferably performed in theorder enumerated: The sheets are hot rolled, sheared, annealed, coldrolled, abraded to remove scale and produce a uniform roughened surfaceon the sheet, continuous wash pickled, scrubbed and dried in order toproperly cleanse the sheet and to impart thereto the desired surface.

For certain uses, the uniform roughened surface of the sheet isdesirable but for other purposes requlring a higher finish, the sheets,after they have been cleansed subsequent to the abrading step, will besubjected to a cold rolling operation for the purpose of smoothing downthe ridges previously explained as having been formed by the abradingaction.

In straight line continuous production of metallic sheets, the followingexamples are illustrations of the manner in which the process comprisingmy invention may be advantageously employed: For sheets which havepassed through the regular finishing process but upon final inspectionshow defects in their surface, such sheets may be reclaimed and a fullfinished surface imparted thereto by causing the same to beabraded inthe manner above defined and then wash pickling and 1 cold rolling thesame in order to remove the defect present in the original finishedstate of the sheet.

Frequently, at an inspection stage preliminary to the usual final coldrolling step, imperfections are noted in the sheet which, in theexperience of the inspector, are of the character such that the coldrolling operation will clearly not remove the same. Accordingly, insteadof permitting such sheet to pass through the cold rolling stage, it willbe found desirable to withdraw such sheet from the regular process andthen immediately subject the same to an abrading action for the purposeof removing the imperfection and imparting thereto a roughened surface,whereupon the sheet may be cold rolled to produce a surface free fromthe noted imperfection.

As previously indicated, strip steel manufactured in the usual processby cold rolling under high pressure, such as exerted by a four-highrolling mill, usually have a surface which is mirror-like in characterand hence, really too smooth for the proper adherence thereto offinishing coats such as paints-enamels and the like. It is one of theobjects of my invention to pass such continuous strip through theapparatus disclosed in my previously identified patent to subject thesame to an abrading action such as forms one of the steps in the processcomprisingmy present invention and by such abrading action, sufllcientlyroughen the surface of the sheet so that it has the appearance, mostclearly illus-- trated in Fig. 2 of the drawing, which is some cientlyuniform so as not to show through the finish coat but suiiiciently openso that such a ish coat may readily adhere thereto.

By the process comprising my invention, the sheets or strips may betreated in a continuous manner for the production of a high-grade iullfinish sheet or such process may be employed for the purpose ofreclaiming sheets previously fin= ished but which, upon inspection,have. been found to contain defects in their surface which cannot beremoved by ordinary processes. The process comprising my invention,therefore, not

only insures an initially high-grade sheet superior to any heretoforeemployed, lout enables sheets having surface imperfections, which wouldnormally cause such sheets to he classified as seconds. to be reclaimedand sold as first-class stock.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the processherein disclosed, provided the step or steps stated by any of thefollowing claims or the equivalent of such stated step or steps beemployed.

I, therefore, particularly point out and distinctly claim as myinvention:

1. The method of finishing metallic sheets which comprises the followingsteps: cold rolling, abrading, continuous wash pickling, scrubbing,drying, and then cold rolling.

2. In a method of prep the adhesion of a non-metallic finish coat, thesteps which comprise removing scale and loosely attached particles fromthe surface of such sheet by abrading in parallel lines and restoringthe smooth surface by cold rolling.

3. In a method of preparing a steel sheet for the adhesion oi anon-metallic finish coat, the steps which comprise removing scale andloosely attached particles from the surface of a commercial cold-rolledsheet by abrading in parallel lines and restoring smoothness to thesurface by coldrolling in the direction of said lines.

t.- In the method of preparing a steel sheet for the esion of a finishcoat, the steps which comprise removing surface defects from the surfaceof such sheet by ahrading in parallel lines, and restoring the smoothsurface by cold rolling.

5. The method of finishing metallic sheets which comprises the followingsteps: cold rolling, abrading, pickling, and then cold rolling.

t. The method of finishing a metallic sheet which comprises thefollowing steps: cold rolling, removing defects from the surface of thesheet without etching the same and then restoring the smooth surface bycold rolling.

'i, The method of finishing a metallic sheet which comprises removingthe surface defects from the sheet by abrading, cleaning the surface ofthe sheet without etching the same, and then restoring the smoothsurface by cold rolling.

Y M. FEN'ION.

